Theoretical and experimental studies of stresses in flexible pipes

This paper presents one model for predicting stresses from axi-symmetric effects and two alternative formulations for predicting bending stresses in tensile armour layers of non-bonded flexible pipes. The models were developed to comply with the framework of non-linear finite element technology allowing direct implementation into existing codes for flexible riser analysis, all based on corotated kinematics allowing for large displacements and small strains. Experimental studies were further carried out using strain measurements from fibre-optic Braggs to validate the performance of both formulations in terms of bending stresses and fatigue.